JP6220129B2 - Protective relay system and protective relay device - Google Patents

Description

  Embodiments described herein relate generally to a protective relay system and a protective relay device.

  2. Description of the Related Art Conventionally, a protective relay system that protects a power system facility by detecting and removing an accident that has occurred in the power system facility such as a transmission line, a bus, and a transformer constituting the power system has been used. For example, in a protective relay system that protects a transmission line, a protective relay device is provided at the end of a section of the power system, each protective relay device is connected by a transmission line, and based on the electrical quantity information at each terminal There is technology to detect accidents.

  Among the protective relay devices, the current differential relay device that protects the transmission line acquires current value information at its own terminal and transmits the current value information to the counterpart terminal via the transmission line. And the protection relay device of the other party terminal which received current value information detects the accident of a transmission line according to the difference of the current value information acquired by the self terminal, and the current value information received via the transmission line . The time (sampling timing) of the current differential relay device at each terminal needs to be synchronized with high accuracy.

  For transmission between protection relay devices in a conventional protection relay system, a microwave and an optical line of about 54 Kbps to 1.5 Mbps are conventionally applied, and high-precision synchronization is realized by transmitting a synchronization frame. In recent years, it has been studied to apply a general-purpose network such as Ethernet (registered trademark), which is advantageous in terms of maintenance and cost, instead of microwaves and optical lines. In a protection relay system using a general-purpose network, a plurality of protection relay devices communicate with each other via a relay device. Therefore, the processing timing of the synchronization frame overlaps with the processing timing of other frames in the relay device, and the synchronization frame Transfer time may be delayed.

  When the transfer time of the synchronization frame is delayed, a difference occurs between the forward transmission time between the protection relay devices and the backward transmission device, and the synchronization accuracy is lowered. When the synchronization accuracy is lowered, the current differential relay device performs a differential operation at different sampling timings, which may cause a malfunction.

JP 2010-56947 A

  An object of the embodiment of the present invention is to provide a protection relay system and a protection relay device capable of realizing highly accurate time synchronization between devices.

An embodiment of the present invention includes a plurality of protection relay devices that protect a power system based on electric quantity data of the power system, and the protection relay that performs communication using a network and a relay device between the protection relay devices. About the system. The protective relay device includes a clock unit that periodically records the timing of sampling the amount of electricity in the power system, the amount of electricity sampled according to the timing of the clock unit, and the other via the network. A relay calculation unit that performs relay calculation based on the electric quantity data stored in the electric quantity frame received from the protection relay device, a random number generation unit that generates a random number, and a random number generated by the random number generation unit A synchronization frame processing unit that determines a timing for transmitting a synchronization frame to another protection relay device via the network, the synchronization frame processing unit storing the sampled electrical quantity data The synchronization frame is transmitted after a predetermined time from the timing of transmitting the electrical quantity frame to be transmitted. To determine the timing.

The block diagram which shows the structure of the protection relay system of 1st Embodiment. The functional block diagram which shows the internal structure of the protection relay apparatus of 1st Embodiment. The figure which shows the operation | movement at the time of synchronizing the clock part 113 of 1st Embodiment. The figure which describes the timing which transmits the synchronous frame of 1st Embodiment. The functional block diagram which shows the internal structure of the protection relay apparatus of 2nd Embodiment. The figure which shows the timing which transmits the synchronous frame of 2nd Embodiment. The block diagram which shows the structure of the protection relay system of 3rd Embodiment. The functional block diagram which shows the internal structure of the protection relay apparatus of 3rd Embodiment.

  A protection relay system and a protection relay device according to an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
The configuration of the protective relay system according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing a protective relay system for protecting a three-terminal power transmission line.

  The protective relay system 1 includes protective relay devices 11-1 to 11-3, relay devices 12-1 to 12-2, and networks 13-1 to 13-4.

  The protective relay devices 11-1 to 11-3 are connected to current transformers 3-1 to 3-3 installed in the vicinity of the terminals 2-1 to 2-3, respectively, and acquire electric quantity data. Further, the protection relay devices 11-1 to 11-3 perform communication via the networks 13-1 to 13-4 and the relay devices 12-1 to 12-2, respectively, and transmit and receive data frames. Here, the data frames transmitted and received between the protective relay devices 11-1 to 11-3 are the electric quantity frames including the electric quantity data acquired by the current transformers 3-1 to 3-3, and the respective protective relays. It is a synchronization frame for performing time synchronization between the devices 11-1 to 11-3.

  The internal configuration of the protective relay device 11-1 will be described with reference to FIG. FIG. 2 is a functional block diagram illustrating a functional configuration of the protective relay device 11-1.

  The protective relay device 11-1 includes an input conversion unit 111, an analog / digital conversion unit (hereinafter referred to as A / D conversion unit) 112, a clock unit 113, an electric quantity frame processing unit 114, a communication unit 115, a relay calculation unit 116, a synchronization A frame processing unit 117 and a random number generation unit 118 are provided. Since the protective relay devices 11-2 and 11-3 installed at the terminals 2-2 and 2-3 have the same configuration as the protective relay device 11-1, the following description is omitted.

  The input conversion unit 111 receives the electric quantity data acquired by the current transformer 3-1 as analog data.

  The A / D conversion unit 112 samples the electric quantity data of the analog data input to the input conversion unit 111 in accordance with the sampling timing periodically engraved by the clock unit 113, and converts it into digital data.

  The electrical quantity frame processing unit 114 converts the electrical quantity data converted into digital data by the A / D conversion unit 112 into an electrical quantity frame via the communication unit 115, the network 13-1, and other relay devices, and the protective relay device 11- 2 and 11-3. Further, the electrical quantity frame processing unit 114 receives the electrical quantity frame of the digital data transmitted from the protective relay devices 11-2 and 11-3 via the network 13-1 and the communication unit 115. The electric quantity frame received here stores the electric quantity data acquired by the current transformers 3-2 and 3-3 of the terminals 2-2 and 2-3.

  The relay calculation unit 116 includes the electrical quantity data of the terminal 2-1 digitally converted by the A / D conversion unit 112 and the terminals 2-2 and 2-3 stored in the electrical quantity frame received by the electrical quantity frame processing unit 114. Current differential calculation is performed based on the electrical quantity data.

  The synchronization frame processing unit 117 transmits a synchronization frame to the protection relay devices 11-2 and 11-3 via the communication unit 115 and the network 13-1. Here, the timing (T0) at which the synchronization frame is transmitted is within a variation allowable time (T2) after a certain time (T1) from the sampling timing, and is determined based on the random number generated by the random number generator 118. Further, the synchronization frame processing unit 117 receives the synchronization frame from the protective relay devices 11-2 and 11-3 via the network 13-1 and the communication unit 115, and corrects the clock unit 113.

  Here, the operation of the protective relay devices 11-1 and 11-2 when correcting the clock unit 113 will be described with reference to FIG. FIG. 3 shows an operation when the protection relay device 11-1 is a slave end, the protection relay device 11-2 is a main end, and the clock portion 113 of the main end, not shown, is synchronized. There are four types of synchronization frames transmitted and received by the protection relay devices 11-1 and 11-2: a polling (Poll) frame, a synchronization request (Req) frame, a synchronization response (Resp) frame, and a transmission time notification (FollowUP) frame. It is divided into.

  The Poll frame is a signal that is transmitted from the main end to the slave end and gives the slave end permission of synchronous communication. The Req frame is a signal transmitted from the slave end to the master end and indicating the start of synchronous communication. The Resp frame is a response return signal that is transmitted from the main end to the subordinate end and indicates a response to the Req frame. The FollowUp frame is a signal that is transmitted from the main end to the slave end and notifies the slave of the transmission time of the Resp frame.

  The above four types of frames are transmitted and received, and the one-way transmission delay time Td is calculated by the following equation (1). Here, the calculation is performed on the assumption that the uplink transmission delay time is equal to the downlink transmission delay time.

Td = {(T 2 −T 1) + (T 4 −T 3)} / 2 (1) Equation From the calculated transmission delay time (Td), the protective relay device 11-1, 11 − A synchronization error (ΔT) between the two clock units is calculated.

ΔT = (T 2 −T 1) −Td (2) Equation The correction is completed by adding or subtracting the synchronization error (ΔT) calculated here to the clock unit 113.

  Next, FIG. 4 shows the transmission timing of the electrical quantity frame and the synchronization frame transmitted from the communication unit 115 to the network 13-1. The electrical quantity frame is transmitted as soon as the electrical quantity data is acquired, while the synchronization frame is transmitted within a variation allowable time (Tb) after a certain time (Ta) from the sampling timing. The allowable variation time (Tb) can be calculated from the allowable accuracy of the synchronous control of the protective relay devices 11-1 to 11-3, and the synchronous control interval is determined from the crystal oscillator accuracy of the device and the required synchronization accuracy between the devices. The time that is n times the communication time of the synchronization frame to be transmitted is defined as the allowable fluctuation time (Tb). That is, the timing (Tc) for transmitting the synchronization frame can be expressed by the following equation (3). Here, K is a random number created by the random number creation unit 118 and satisfies 0 ≦ K ≦ 1.

Tc = Ta + (Tb × K) (3) According to the present embodiment, the protection relay is performed by determining the timing for transmitting the synchronization frame based on the random number determined by each protection relay device. In the relay devices 12-1 and 12-2 of the system 1, it is possible to suppress the occurrence of a transmission delay time caused by overlapping synchronization frame relay processing. That is, it is possible to suppress malfunction of the protective relay device by improving the synchronization accuracy of the clock unit between the protective relay devices.

  In this embodiment, the allowable variation time (Tb) is set after a certain time (Ta) from the sampling timing. This fixed time (Ta) is set so that the protective relay device 11-1 on the transmission side sets the electrical quantity frame to be longer than the time required for the transmission process, so that the electrical quantity frame transmission process gives the synchronization frame transmission process. It is possible to reduce the influence.

  In addition, by setting the fluctuation allowable time (Tb) to n times the communication time of the synchronization frame transmitted at a fixed period, the probability that the synchronization frame transmitted from another device collides with the relay device is about 1 / n. Is possible.

  In addition, the synchronization frame processing unit 117 holds the random number generated by the random number generation unit 118, and when the same random number is continuously acquired, the synchronization frame processing unit 117 is configured to acquire the random number again, thereby further protecting relaying. It becomes possible to improve the synchronization accuracy of the devices 11-1 to 11-3.

  Further, the synchronization frame processing unit 117 stores the transmission delay time (Td) calculated by the equation (1) in a storage unit (not shown) as needed, and the transmission calculated as the minimum minimum delay time among the past transmission delay times. The delay time (Td) may be compared. When the difference between the minimum delay time and the calculated transmission delay time (Td) is greater than or equal to a preset threshold value, the clock unit 113 is not corrected using the transmission delay time (Td). By adopting such a configuration, it becomes possible to synchronously control the clock unit without using data when the transmission delay time (Td) becomes larger than normal, such as when a transmission abnormality occurs, The accuracy can be improved.

  However, as described above, when Td is stored and compared with the minimum delay time, the communication path changes due to a defect in the network or relay device, and it is necessary to perform synchronous control after the path changes. The Td that is not used for correction is also stored in the storage unit as a sample. The storage unit stores a certain amount of past data, but if there are few samples, the chance of adopting Td that includes relay delay variation increases and the synchronization accuracy becomes unstable, and if the number of samples is large, the transmission delay time changes due to path change. The time required to follow increases. The number of samples to be stored is the same idea as described above, and the time required to follow the path change is determined from the required inter-device synchronization accuracy and the synchronization control interval. Is required.

  In the present embodiment, the electrical quantity frame and the synchronization frame are described as separate data frames for the sake of simplicity. However, the electrical quantity frame and the synchronization frame may be the same frame. The added frame is treated as a synchronization frame, and the transmission timing is determined based on a random number.

(Second Embodiment)
The protection relay device of 2nd Embodiment is demonstrated using FIG. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The difference from the first embodiment is that a storage unit 119 is provided instead of the random number generation unit 118 and a synchronization frame processing unit 117-1 is provided instead of the synchronization frame processing unit 117.

  The synchronization frame processing unit 117-1 transmits a synchronization frame to the protection relay devices 11-2 and 11-3 via the communication unit 115 and the network 13-1. Here, the timing (Tc) at which the synchronization frame is transmitted is within the fluctuation allowable time (Tb) after a certain time (Ta) from the sampling timing.

  The transmission is performed at the timing obtained by adding the addition time (Δt) from the transmission timing of the previous synchronization frame within the fluctuation allowable time (Tb). That is, if the first transmission timing (Tc1) is “after a fixed time (Ta)” from the sampling timing, the second transmission timing (Tc2) is “fixed time (Ta) + addition time (Δt)” from the sampling timing. "Send later.

  Then, at the nth time (here, a value obtained by dividing the variation allowable time (Tb) by the addition time (Δt) is n), the transmission timing (Tcn) is “fixed time (Ta) + addition time (Δt) × (n -1) ".

  The transmission timing described above is shown in FIG. The electric quantity frame is transmitted as soon as the electric quantity data is acquired, whereas the synchronous frame is transmitted within a variation allowable time (Tb) after a certain time (Ta) from the sampling timing, and the transmission timing is set for the addition time (Δt) each time. Delay.

  Then, a synchronization frame is transmitted at each transmission timing (Tc), and a transmission delay time Td is calculated by the equation (1) shown in the first embodiment.

  The storage unit 119 stores the minimum value of the transmission delay times calculated in the past by the synchronization frame processing unit 117 as the minimum delay time. That is, the synchronization frame processing unit 117 compares the calculated transmission delay time (Td) with the minimum delay time stored in the storage unit 119, and minimizes the value if the transmission delay time (Td) is smaller. Overwrite as delay time. At this time, the transmission timing (Tc) of the synchronization frame is also stored. That is, the transmission timing of the synchronization frame having the minimum delay time with the minimum transmission delay time (Td) is searched.

  Then, the synchronization frame processing unit 117 uses the (n + 1) th and subsequent synchronization frame timings by fixing the transmission timing that is the minimum delay time stored in the storage unit 119.

  According to the present embodiment, the timing at which the transmission delay time (Td) is minimized can be determined by changing the timing at which the synchronization frame processing unit 117 transmits the synchronization frame every time. After the determination, by using the transmission timing that is the minimum, the relay devices 12-1, 12-2, etc. of the protection relay system 1 can generate the transmission delay time caused by the overlapping of the synchronization frame relay processing. Can be suppressed. That is, it is possible to suppress malfunction of the protective relay device by improving the synchronization accuracy of the clock unit between the protective relay devices.

  In this embodiment, the transmission delay time (Td) is that of the network configuration and communication load at the time of calculation, and the increase / decrease in the number of terminals and the number of data frames / frame length / communication cycle / communication form (unicast, multicast). Etc. are changed, the transmission delay time (Td) also changes. Therefore, when there is a change related to these communications, the minimum delay time stored in the storage unit 119 is deleted, and high-precision synchronization is performed after the change by performing the above-described operations 1 to n again. realizable.

  In addition, since the synchronization method described above is led by the main end and performs synchronous communication using a Poll frame, collisions with the synchronization frame are limited to frames that are regularly transmitted, such as electric quantity frames. Frames do not collide (no coordination between terminals is required). However, depending on the time synchronization method, there are cases where the slave is led. In this case, there is a possibility that the synchronization frames collide with each other because each slave end transmits the synchronization frame at an arbitrary timing. The advantage of slave-driven is that the Poll frame is unnecessary, so the communication load can be reduced, and since slave-driven, the synchronization communication cycle can be set according to the synchronization accuracy required by each slave and the clock accuracy of each slave (there is The terminal has a low clock accuracy, so 100 ms synchronous communication + synchronization correction, and another terminal has a high clock accuracy, so a 10 second period is OK).

  In the present embodiment, the period other than the period in which communication / passage is always performed, such as an electric quantity frame, is obtained. In the edge-driven method, even if the minimum delay time is obtained as in the above embodiment, there is a possibility of colliding with a synchronization frame transmitted from another terminal.

  When a collision occurs with a synchronization frame sent from another terminal, the calculated transmission delay time (Td) changes and does not coincide with the minimum delay time. However, since the Td change is detected by a plurality of terminals when the synchronization frames collide with each other, if each of them is re-searched at the same time, the frame will collide every time if the synchronization communication period is the same even if the addition time is added to the transmission timing. .

  In order to avoid this, if the mismatch with the minimum delay time continues m times, the search can be started again. Setting m times may be a numerical value that is difficult to duplicate, such as using a terminal number of each terminal or a part of the host address of the IP address, and a priority number may be set in advance in the same system. As another method, a unit to be added to the transmission delay at the time of searching for the minimum delay time in the first to n-th operations described above and a part of the terminal number or host address so that the synchronization communication cycle does not overlap in each terminal. Continuing the frame collision can also be avoided by diverting.

(Third embodiment)
The configuration of the protective relay system according to the third embodiment of the present invention will be described with reference to FIG. FIG. 7 is a block diagram illustrating a protective relay system that protects a three-terminal power transmission line.

  The protective relay system 1 includes protective relay devices 11-1 to 11-3, relay devices 12-1 to 12-2, and networks 13-1 to 13-4.

  The protective relay devices 11-1 to 11-3 are connected to current transformers 3-1 to 3-3 installed in the vicinity of the terminals 2-1 to 2-3, respectively, and acquire electric quantity data. Further, the protection relay devices 11-1 to 11-3 perform communication via the networks 13-1 to 13-4 and the relay devices 12-1 to 12-2, respectively, and transmit and receive data frames. Here, the data frames transmitted and received between the protective relay devices 11-1 to 11-3 are the electric quantity frames including the electric quantity data acquired by the current transformers 3-1 to 3-3, and the respective protective relays. It is a synchronization frame for performing time synchronization between the devices 11-1 to 11-3.

  The internal configuration of the protective relay device 11-1 will be described with reference to FIG. FIG. 8 is a functional block diagram illustrating a functional configuration of the protective relay device 11-1.

  The protective relay device 11-1 includes an input conversion unit 111, an analog / digital conversion unit (hereinafter, A / D conversion unit) 112, a clock unit 113, an electrical quantity frame processing unit 114, a communication unit 115, and a relay calculation unit 116. Prepare. Since the protective relay devices 11-2 and 11-3 installed at the terminals 2-2 and 2-3 have the same configuration as the protective relay device 11-1, the following description is omitted.

  The input conversion unit 111 receives the electric quantity data acquired by the current transformer 3-1 as analog data.

  The A / D converter 112 samples the electrical quantity data of the analog data input to the input converter 111 in accordance with the sampling timing engraved by the clock unit 113, and converts it into digital data.

  The electrical quantity frame processing unit 114 converts the electrical quantity data converted into digital data by the A / D conversion unit 112 into an electrical quantity frame via the communication unit 115, the network 13-1, and other relay devices, and the protective relay device 11- 2 and 11-3. Further, the electrical quantity frame processing unit 114 receives the electrical quantity frame of the digital data transmitted from the protective relay devices 11-2 and 11-3 via the network 13-1 and the communication unit 115. The electric quantity frame received here stores the electric quantity data acquired by the current transformers 3-2 and 3-3 of the terminals 2-2 and 2-3.

  At this time, the reception time is held every time the electric quantity frame is received, and the time difference between the reception time of the electric quantity frame received last time from the same transmission source and the current reception time is set to a preset threshold (K1). ) If this is the case, the electric quantity frame received this time is discarded. In other words, when an electrical quantity frame is periodically received from the protective relay device of the same transmission source, but the interval between reception times is equal to or greater than the threshold (K1), it is determined that an abnormality has occurred in the network between the devices. And discard the abnormal electricity quantity frame. The threshold value K1 here is expressed as, for example, K1 = (transmission cycle of the transmission source protection relay device) + α.

  The relay calculation unit 116 includes the electrical quantity data of the terminal 2-1 digitally converted by the A / D conversion unit 112 and the terminals 2-2 and 2-3 stored in the electrical quantity frame received by the electrical quantity frame processing unit 114. Current differential calculation is performed based on the electrical quantity data.

  According to the present embodiment, when the interval between the reception times of the electrical quantity frames is equal to or greater than the threshold, the electrical quantity frame may be discarded to cause network abnormality such as a frame collision in the network. Relay calculation is possible without using quantity frames. Therefore, it is possible to suppress malfunction of the protective relay device 11-1.

  Further, in the present embodiment, the frame is discarded when the reception interval of the electrical quantity frame is equal to or greater than the threshold, but the frame to be discarded is not limited to the electrical quantity frame, and may be a synchronization frame, In this case as well, the synchronization frame is discarded when the reception interval is equal to or greater than the threshold value.

  Further, as shown in the first embodiment, the present embodiment can also be applied to the case where the transmission timing of the synchronization frame is determined based on a random number. In this case, the threshold (K2) is K2 = (source protection) It is expressed as (transmission cycle of relay device) + (variable allowable time (T2)) + α.

  According to the embodiments of the present invention, it is an object to provide a protective relay system, a protective relay device, and a time synchronization method capable of realizing highly accurate time synchronization between devices.

  As mentioned above, although some embodiment of this invention was described, these embodiment was shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Protection relay system 2-1 to 2-3 ... Terminals 3-1 to 3-3 ... Current transformer 4 ... Transmission line 11-1 to 11-3 ... Protection relay device 12-1 to 12-2 ... Relay devices 13-1 to 13-4 ... Network 111 ... Input conversion unit 112 ... A / D conversion unit 113 ... Clock unit 114 ... Electric quantity frame processing unit 115 ... Communication unit 116 ... Relay operation unit 117 ... Synchronous frame processing unit 118 ... Random number generator

Claims (4)

In a protection relay system that includes a plurality of protection relay devices that protect the power system based on the electrical quantity data of the power system, and that communicates between the protection relay devices using a network and a relay device ,
The protective relay device is
A clock unit that periodically ticks the timing of sampling the amount of electricity in the power system;
Relay calculation based on the electric quantity data sampled in accordance with the timing of the clock unit and the electric quantity data stored in the electric quantity frame received from another protective relay device via the network A relay calculation unit for performing
A random number generator for generating random numbers;
A synchronization frame processing unit that determines a timing for transmitting a synchronization frame to another protection relay device via the network based on the random number generated by the random number generation unit;
Bei to give a,
The protection frame relay system, wherein the synchronization frame processing unit determines a timing for transmitting the synchronization frame after a predetermined time from a timing for transmitting the electrical quantity frame storing the sampled electrical quantity data . The protection relay system according to claim 1, wherein when the same random number is continuously acquired from the random number generation unit, the synchronization frame processing unit determines the timing based on the acquired random number again. The synchronous frame processing unit, in the pre-configured variation allowable time, protection relay system as claimed in claim 1 or 2 for determining the timing of transmitting the synchronization frame. In the protective relay device that protects the power system based on the electricity quantity data of the power system and communicates with other devices using the network and relay equipment ,
A clock unit that periodically ticks the timing of sampling the amount of electricity in the power system;
Relay calculation based on the electric quantity data sampled in accordance with the timing of the clock unit and the electric quantity data stored in the electric quantity frame received from another protective relay device via the network A relay calculation unit for performing
A random number generator for generating random numbers;
A synchronization frame processing unit that determines a timing for transmitting a synchronization frame to another protection relay device via the network based on the random number generated by the random number generation unit;
Bei to give a,
The synchronization frame processing unit is a protection relay device that determines a timing for transmitting the synchronization frame after a predetermined time from a timing for transmitting the electrical quantity frame storing the sampled electrical quantity data .

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